This always happened to me as well and I tried many of the same things you did with no success.
...until last spring
I replaced my a/c compressor with a reman unit and pulled a good OEM fan clutch from a junked Rodeo. I think the fan clutch fixed the problem but I couldn't tell you for sure. The fan clutch pulls a lot more air than my old stock fan clutch but less than autozone's torflo unit which is way too tight for our engine.
Thoughout Moab and all summer I was blasting a/c with a heavy foot and the temp gauge never moved up a tick.